The term user interface in this context refers to a Lua script asking questions of a user and/or presenting information to a user. A user interface can be as simple as asking for confirmation to perform an action or as complex as a product configurator asking for many specification elements.

The welcome wizard you saw when you first installed Match-IT contains a simple user interface asking for various setup options.

Almost anything you see in a built-in Match-IT window can also be done in a window created by GUILE (GUILE is the name used to refer to the facilities described in this manual).